It is assumed that there can be two types of maintenance.

The first is scheduled maintenance that must be performed every six months. It must be focused on replacement of all worn parts that cannot adequately guarantee for another six months of operation.

The hypotheses that can currently be advanced are: replacement of belts and ball bearings, replacement and/or sharpening of grinder blades, replacement of ventilator heating elements used to eliminate moisture or the ventilators themselves, replacement of the lenses in optical compressor oil level sensors, water pump (see the real hours of operation guaranteed by the manufacturer).

To perform this type of maintenance the machine must be down for 4 days (one for each type of hopper) and 4 containers are required to receive any wastes delivered during the maintenance period. Such maintenance is to be organized as follows:

1. Pick-up of all materials needed for maintenance from storage. Time required: 5 hours x 4 people = 20 h.
2. The skilled, scheduled maintenance team goes to the Green Island to be maintained with the following equipment: truck with crane boom rated to bear 1.5 t, van with the necessary tools, a container for temporary storage of the wastes and all the spare parts indicated above. It would be useful to have an awning structure to cover the area in case of bad weather and ensure adequate work. Time required: 1.5 hours x 4 people = 6 h.
3. The procedures can be described as follows:
   
4. The team arrives on site after having notified the population that, if possible, they should refrain from delivering wastes on those days as scheduled maintenance will be in progress. On the trip to the site, those who are not driving must re-read the status report and familiarize themselves with the current conditions of the machine. Once on site, they must protect the area, fencing it off to prevent anyone not involved in the work from hindering the operations or being injured.
5. After having fenced off the area, the hatches must be opened, the air conditioners turned on to create a microclimate suitable for performing work in the center. All utilities of any type are closed off and arranged in the center’s underground hallway. Time required: 2 hours x 4 people = 8 h.
6. The cables connecting the units and the body of the hoppers are disconnected, the screws located at the lower front of the hoppers are removed and the hoppers are withdrawn. The skid-proofing strips are removed from the flooring and the hatch on the back of the panel is opened.
7. With access from the front hatch, the hopper is withdrawn by approximately 50 cm. Then the workers walk around to the back of the hopper to disconnect the connection pins. It is then pulled out all the way and brought to the truck for diagnostics. The same procedure is used to remove the other hoppers. Estimated time: 1.5 hours x 4 people = 6 h.
8. At this point one has free access to test the grinders and check blade sharpness. This can be performed using a limited sample of wastes to determine whether the blades are to be replaced or sharpened. If the blades do require sharpening or replacement, the grinder must be removed and a new or regenerated one installed, but only at the final phase. Time required: 2 hours x 4 people = 8 h.
9. The second operation is as follows: Two people pass through the manholes and enter the center, removing the locks on the roof of the machine (which is divided into four parts). Using the hydraulic system on the crane truck and the two hooks supplied for each opening, all four parts of the machines are opened. Time required: 2 h x 2 people = 4 h. Once open, all parts of the machine can be inspected.
10. All parts are checked by the specialists and the person responsible for the sector of the machine. Unless unexpected events occur, the time required for this is 3 hours x 4 people = 12 h.
11. The time estimate for installation of spare parts and replacement pieces, considering installation of only 3 grinders, including dissipator, is 3 hours x 4 people = 12 h.
12. Cleaning and assembly of the machine takes another 3 hours x 4 people, plus one site director and 1 foreman totaling another 32 h.
13. Taking the wastes delivered to the mobile containers by the users and placing it in the center: 30 minutes x 4 people = 2 h.
14. Return to the starting base: 1.5 x 4 = 6 h.
15. Drawing up the report: 1 hour x 4 + 4 for unexpected events.